The invention relates generally to the field of digital data processing systems for distributed monitoring and control in industrial environments, and in particular to a compact, modularly expandable controller (called herein a xe2x80x9cfield controllerxe2x80x9d) and internal dongles adapted for use with the controller.
Distributed control systems are often used in a number of commercial, industrial and home applications, in particular to monitor and control operations at manufacturing, chemical processing and similar industrial operations, to monitor and control environmental and other factors and so forth. In a manufacturing operation, a distributed control system will typically control machines which facilitate the manufacture and assembly of the products being manufactured. In addition, in a chemical processing operation, a distributed control system may control valves to control rates of flow of chemicals into and out of reaction chambers, and monitoring and/or controlling reaction temperatures and pressures and the like which are required to carry out the chemical process. In addition to controlling the manufacturing or chemical process, distributed control systems may perform bookkeeping operations to keep track of the inventory of inputs required for the manufacturing or chemical process, as well as the inventory of outputs produced by the operation. Typical distributed control systems essentially comprise large, centrally-located and expensive computer systems, which can be expensive to maintain and typically have limited expansion capabilities.
A control system may include one or more PCMCIA cards that each couple to a device in the industrial environment, such as, for example, an instrument, monitor, machine or the like. Often, it is advantageous to include an active or passive circuit in the coupling between the controller and the device. The cable may include the circuit. In one arrangement, called a xe2x80x9cdongle,xe2x80x9d the cable has an encapsulated end portion that includes the active or passive circuit and a connector.
The invention provides a relatively compact, computationally powerful, easily-extendable and easily serviceable field controller for use in a variety of industrial, commercial and home applications.
According to one aspect of the invention, a field controller for use in a distributed control system with an area controller manages at least one controlled device in an industrial process operation. The field controller includes a processor module segment through which it can control a selected number of devices. The field controller may also include one or more expansion module segments, each having at least one PCMCIA card coupled to the process control segment to enable it to control a larger number of controlled devices. The processor module segment includes a processor module and at least one local interface module for interfacing to a controlled device, and the expansion module segment includes interface modules for interfacing to other controlled devices. In the processor module segment, the processor module and the local interface module are interconnected by a bus segment, which is also connected to an upstream off-module connector. Each expansion module segment includes at least one interface module, and also includes a downstream off-module connector and an upstream off-module connector, which are interconnected by a bus segment. The downstream off-module connector of each expansion module segment is adapted to mate with the upstream off-module connector of the processor module segment and of other expansion module segment, so as to facilitate the interconnection of the processor module segment and a sequence of expansion module segments by establishing a unitary multi-drop bus comprising the processor module""s bus segment and the bus segments of expansion module in the sequence. The processor module controls each controlled device through the respective local interface module or expansion interface module connected thereto. The processor module segment and each expansion module segment are each mounted in a housing segment which is configured to form a unitary housing when they are interconnected.
A benefit of this arrangement is that the number of controlled devices which can be controlled by the field controller be easily increased or decreased by adding expansion module segments to, or removing them from, the field controller. Since the bus created by the series of bus segments is an extensible multi-drop bus, the controlled devices can be connected to the field controller through any interface module connected into the field controller along the bus. Since the processor module segment and each expansion module segment also includes an integral housing segment, when the processor module segment and expansion module segments are connected together they provide a unitary, compact housing which is convenient in a commercial, industrial or home environment.
According to another aspect of the invention, an industrial computing device, such as a field controller, includes a field mountable housing. The housing includes a primary housing with first and second side covers, and a removable front cover. The first side cover is structured and arranged to provide access to a processor within the housing from a first lateral side of the primary housing. The first side cover includes a mount on a rear side structured and arranged to mount the housing to a DIN rail. The mount is adapted to electrically connect to a ground bus within the primary housing with the first side cover coupled to the primary housing. At least one peripheral connector within the housing is adapted to receive at least one PCMCIA card such that when the PCMCIA card is plugged into the peripheral connector, the PCMCIA card is also within the housing and electrically coupled to the processor. An expansion connector is adapted to receive an expansion board which includes at least one more peripheral connector which itself is adapted to receive at least one more PCMCIA card. The second removable side cover is structured and arranged to provide access to the expansion connector from a second lateral side of the primary housing. The peripheral connector, the expansion connector, the primary housing and the first and second side covers are oriented orthogonal to a mounting plane of the industrial computing device.
The primary housing includes I/O structure for mounting at least one I/O connector in a recess of the housing such that it is integral with the housing. The recess may be provided between the front cover and a hinged lid at a top or bottom end of the primary housing. A ground bus includes a connector which is structured and arranged to electrically couple to a body of the I/O connecter when mounted to the housing. The I/O connector may be an internal dongle which includes a body including connective structure being arranged to removably attach the body to the primary housing, and a circuit assembly, including an exterior connector on the body for electrically connecting to an external electronic device, a dongle circuit being electrically coupled to the external connector through the body, an electronic cable having a first end electrically coupled to the dongle circuit, and a second end including a connector being structured and arranged to connect to an electronic component within the housing, such as, for example, the PCMCIA card. The dongle circuit may include a passive circuit, an active circuit, or both on a circuit board attached to the body.
The industrial computing device may further include an expansion module which includes the expansion board in an expansion housing. The expansion module mechanically couples between the primary housing and the second side cover and is oriented orthogonal to the mounting plane of the industrial computing device. Each of the primary housing and the expansion housing including a recess and other structure for mounting at least one I/O connector integral with the primary housing and the expansion housing, respectively. The expansion module may further include a second expansion connector adapted to receive a second expansion board in a second expansion module. The second expansion board includes at least one more peripheral connector being adapted to receive at least one more PCMCIA card. An addressing circuit automatically assigns the PCMCIA cards unique addresses wherein individual addressing of the PCMCIA cards is unnecessary.